runtime(help): Add Vim lang annotation support for codeblocks

closes: #16215

Co-authored-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Shougo Matsushita <Shougo.Matsu@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/syntax/help.vim b/runtime/syntax/help.vim
index ae7e3bc..3886164 100644
--- a/runtime/syntax/help.vim
+++ b/runtime/syntax/help.vim
@@ -1,7 +1,7 @@
 " Vim syntax file
 " Language:	Vim help file
 " Maintainer:	The Vim Project <https://github.com/vim/vim>
-" Last Change:	2024 Oct 16
+" Last Change:	2024 Dec 15
 " Former Maintainer:	Bram Moolenaar <Bram@vim.org>
 
 " Quit when a (custom) syntax file was already loaded
@@ -15,10 +15,22 @@
 syn match helpHeadline		"^[A-Z.][-A-Z0-9 .,()_']*?\=\ze\(\s\+\*\|$\)"
 syn match helpSectionDelim	"^===.*===$"
 syn match helpSectionDelim	"^---.*--$"
+
+unlet! b:current_syntax
+" sil! to prevent E403
+silent! syntax include @VimScript syntax/vim.vim
 if has("conceal")
   syn region helpExample	matchgroup=helpIgnore start=" >$" start="^>$" end="^[^ \t]"me=e-1 end="^<" concealends
-else
-  syn region helpExample	matchgroup=helpIgnore start=" >$" start="^>$" end="^[^ \t]"me=e-1 end="^<"
+  syn region helpExampleVimScript matchgroup=helpIgnore
+        \ start=/^>vim$/ start=/ >vim$/
+        \ end=/^[^ \t]/me=e-1 end=/^</ concealends
+        \ contains=@VimScript keepend
+ else
+   syn region helpExample	matchgroup=helpIgnore start=" >$" start="^>$" end="^[^ \t]"me=e-1 end="^<"
+   syn region helpExampleVimScript matchgroup=helpIgnore
+         \ start=/^>vim$/ start=/ >vim$/
+         \ end=/^[^ \t]/me=e-1 end=/^</
+         \ contains=@VimScript keepend
 endif
 if has("ebcdic")
   syn match helpHyperTextJump	"\\\@<!|[^"*|]\+|" contains=helpBar